Object oriented data may be stored in a relational database. A relation database is collection of one or more tables, or relations, of data organized into rows and columns. Each table in the relational database may include columns that represent categories of information. Each table may also include rows that represent a unique instance of data for a category within a column. For example, a table in a relational database may include information relating to customer information. Each column in the table may display categories of customer information, such as name, address, and telephone number. Each row in the table may display specific instances of each category for each specific customer.
Since a relational database may store data in more than one table, data within separate tables in the relational database may need to be connected through a mapping process to create a reference between specific items of data. A reference relates to a connection between data within a relational database.